Synthesis of Mn2O3 microstructures and their energy storage ability studies

α-Mn2O3 microstructures, including spheres and polyhedrons, were fabricated through a two-step process: MnF2 precursor was first hydrothermally synthesized using manganese acetate and hydrofluoric acid in ethanol, and then pyrolyzed to α-Mn2O3 at 350 °C. α-Mn2O3 morphologies were controlled through MnF2 precursors by adjusting HF/Mn(CH3COO)2 molar ratio and solvents. Spherical α-Mn2O3 particles were formed when HF/Mn(CH3COO)2 molar ratio was 2:1, and polyhedral α-Mn2O3 particles were prepared and particle size increased when the molar ratio increased to 12:1. Solvent viscosity affected Mn2O3 morphologies and particle size. Irregular particles of α-Mn2O3 with larger size were formed as aqueous solvent was substituted for ethanol. Smaller particles of α-Mn2O3 were formed when glycerol was used instead. The discharge mechanism and cycling stability of α-Mn2O3 electrode materials were studied. Spherical α-Mn2O3 exhibited excellent lithium storage capacity of 2899 mAh g−1 at first cycle and 265 mAh g−1 after 15 cycles. The formation of LiAl alloy did much contribution to the discharge capacity of first cycle. As for supercapacitor electrode materials, α-Mn2O3 was transformed into burserite during charge/discharge process, and capacitance increased with the increase of surface area. The highest specific capacitance was 202 F g−1 and kept steady after 400 cycles. The as-prepared α-Mn2O3 with various microstructures might be applied as rechargeable electrode materials for lithium-ion battery and supercapacitor.